Patients with well-documented chronic hepatitis C are being evaluated to determine the long-term natural history of this common form of chronic liver disease. A cohort of such patients are available to evaluate experimental therapies. Previous studies have shown that alpha interferon therapy has a short-term beneficial effect in approximately 50% of sustained in approximately 20% after stopping interferon. A randomized, placebo-controlled trial of ribavirin is currently underway. So far, 32 of 58 patients have completed the first year of the study. Prolonged ribavirin administration was associated with significant improvement in serum aminotransferase activities and in hepatic lobular necrosis despite unchanged serum levels of HCV RNA.